<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title>24.子表达式</title>
	</head>
	<body>
		<script type="text/javascript">
			/* 子表达式-引用 */
			let reg = /(\w)\1(\w)\2\1/g;    /* 规律匹配 xxyyx*/
			let str = "aabba";
			console.log(str.match(reg));
		</script>
	</body>
</html>
